Measurement of the inclusive D∗± production in γγ collisions at LEP

Abstract

The inclusive production of D∗± mesons in two-photon collisions is measured with the ALEPH detector at e+e- centre-of-mass energies from 183 GeV to 209 GeV. A total of 360±27 D∗± meson events are observed from an integrated luminosity of 699pb-1. Contributions from direct and single-resolved processes are separated using the ratio of the transverse momentum pD∗±t of the D∗± to the visible invariant mass Wvis of the event. Differential cross sections of D∗± production as functions of pD∗±t and the pseudorapidity |ηD∗±| are measured in the range 2 GeV/c<pD∗±t<12 GeV/c and |ηD∗±|<1.5. They are compared to next-to-leading order (NLO) perturbative QCD calculations. The extrapolation of the integrated visible D∗± cross section to the total charm cross section, based on the Pythia Monte Carlo program, yields σ(e+e−→e+e−cc¯)⟨s√⟩=197GeV=731±74stat±47syst±157extrpb .